/Engine/Plugins/Runtime/MeshModelingToolset/Source/MeshModelingTools/Public/EditMeshPolygonsTool.h
Split each of the selected faces into a separate polygon for each triangle
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(CallInEditor, Category=FaceEdits, Meta=(DisplayName="Decompose", DisplayPriority=10)) void Decompose()